Crystal structure studies of hydrazido(2–)quinolin-8-olato-complexes of molybdenum and tungsten

Abstract

Crystalline samples of five complexes of the formula [M(NNH₂)(quin)(PMe₂Ph)₃]X, where quin = quinolin-8-olate, M = Mo or W, X = I, Br, or Cl, have been examined by X-ray diffraction methods to observe structural differences which would account for differences in protonation reaction products. From complete analysis of three crystals, with (M,X)=(W,I), (Mo,I), and (Mo,Br), the metal, in the cationic complex, is found in almost identical octahedrally co-ordinated environments. In each case, the M–N–N system is linear and the hydrazido-hydrogen atoms are both strongly hydrogen-bonded to anions. Differences are found in (i) the extended hydrogen-bonding schemes, (ii) the position of one of the anions with respect to the cation, and (iii) the orientations of the substituted phosphine ligands.